Aggregation of childhood leukemia in geographic areas of Greece.

A total of 872 children aged up to 14 years, who were diagnosed with leukemia in Greece during the decade 1980-89, were allocated by place of residence to the 601 administrative districts of the country. Evaluation of spatial clustering was done using the Potthoff-Whittinghill method, which validly assesses heterogeneity of leukemia risk among districts with variable expected numbers of cases. There was highly significant evidence for spatial clustering occurring particularly among children living in urban and, to a lesser extent, semi-urban areas. The evidence was stronger for children younger than 10 years old, applied also to children in different five-year age groups, and persisted when cases of acute lymphoblastic leukemia were analyzed separately. These findings provide support to the hypothesis that localized environmental exposures could contribute to the etiology of childhood leukemia, but they cannot distinguish between exposures of physical or chemical nature, nor can they exclude socially conditioned patterns of exposure to infectious agents.

Serum immunoglobulin G subclasses in healthy infants and children in Greece.

Serum concentrations of immunoglobulin IgG1, IgG2, IgG3 and IgG4 were determined by radial immunodiffusion in a sample of 414 healthy Greek children, who were admitted to the major Teaching Hospital for Children in Athens for minor surgical operations. Statistical analysis was performed by multiple regression after logarithmic transformation of the immunoglobulin values. There was a statistically significant increase of IgG3 with age, whereas IgG1, IgG2 and IgG4 levels reached a turning point at the age of five years. Older than 5 years male children were found to have marginally higher IgG4 levels than females. Low socioeconomic class was positively and significantly associated (9% increase) with IgG1 levels only among the older age group. History of frequent infections was associated with a 16% increase of IgG1 levels in the younger (less than 5 years) (p = 0.01) and with a 47% increase of IgG4 among the older age group (p = 0.03). Atopic history was associated with a 16% increase of IgG1 in the younger (p = 0.02). The findings of the present study provide an insight on the determinants and the clinical significance of IgG subclass levels among children.

Sociodemographic and dietary factors in relation to dental health among Greek adolescents.

In the context of a project aiming to assess risk factors affecting health status of Greek adolescents, 380 adolescents aged 12-17 years were randomly selected from two rural high schools of similar socioeconomic status, and from two urban schools of different socioeconomic level, namely urban/lower and urban/ higher. Dental examinations were carried out according to WHO diagnostic criteria; oral hygiene habits were recorded through personal interviews; and diet was assessed through interviewer-administered, semi-quantitative food frequency questionnaires. The percentage of caries-free adolescents varied from 24.3 in the age group of 12-13 years to 13.2 in the age group 16-17 years; mean (SE) DMFT values were 3.7 (0.3) in the younger age group and 5.9 (0.4) in the older age group whereas mean (SE) DMFS values were respectively 5.6 (0.5) and 9.9 (0.9). Multiple regression analysis-derived results showed that dental health, measured through either DMFT or DMFS indices, was significantly better among younger and male adolescents; among higher socioeconomic class urban residents; among those brushing their teeth at least once per day; and among those who had better school performance. There was evidence that intake of vegetables and milk products was associated with lower DMFS and DMFT indices, whereas there was a non-significant tendency for sugar intake to be associated with higher values of these indices. In contemporary Greek society there are substantial social inequalities with respect to dental health; these are due, in part, to differences in oral hygiene habits and patterns of dietary intakes. High risk groups should be identified among the underprivileged for targeted health education efforts and delivery of more intensive dental care services.

Risk factors for injuries among the elderly in Greece.

Extrinsic and intrinsic risk factors for injuries among the elderly in Greece were investigated in a hospital based case-control study. Cases were 200 elderly persons, residents of the Greater Athens area, who contacted the "Laiko" University Hospital for accident-related injuries, during a 10-month period, whereas the control series comprised 385 elderly who, during the same period, contacted the same hospital for non-injury related medical reasons. Data were analyzed by modeling through multiple logistic regression. Statistically significant associations were found for smoking vs non-smoking [odds ratio (OR) 2.40; 95% confidence interval (CI) 1.22-4.70], moderate use of alcoholic beverages vs non use (OR 0.37; CI 0.23-0.61) and house safety score (OR 0.72; CI 0.56-0.93 for an improvement by 1 unit). Non statistically significant positive associations were noted with history of previous hospitalizations for injury, chronic central nervous system conditions, defective hearing, refractive eye disorders, current use of psychoactive drugs, excessive use of alcoholic beverages, other than ground floor residency, cohabitation with fewer members and other than currently married status. Restricted activity was assessed in subsamples of cases and controls and was associated with somewhat reduced risk for injury (OR for one unit increase in a 10 unit modified Groningen activity scale is 1.06; CI 0.99 to 1.13). Overall, these results suggest that there is a constellation of plausible risk factors for injuries among the elderly.

Space-time clustering of childhood leukaemia in Greece: evidence supporting a viral aetiology.

The method introduced by Knox for evaluation of space-time clustering has been applied to 872 cases of childhood (0-14 year old) leukaemia diagnosed in Greece over the 10 year period 1980-89. Greek towns are characterised by substantial population mixing due to internal migration, whereas there is relative isolation in mountainous rural areas. Predetermined space (5 km) and time (1 year) limits were used on the basis of previous reports in order to define the clustering cell. There is highly significant evidence for clustering of childhood leukaemia in Greece as a whole, the observed number of pairs that are close in both spaces and time exceeding the expected number by 5.2% (P = 0.004). The excess is particularly evident for leukaemia cases in 0 to 4-year-old children, among whom the observed number of pairs that are close in both space and time exceeded the expected number by 9.4% (P = 0.004). There is no evidence of space-time clustering for leukaemia cases older than 5 years. The overall pattern is descriptively similar in urban and semiurban areas and is especially marked for acute lymphoblastic leukaemia at the childhood peak ages (2-4 years) with an excess of 19% (P = 0.0006). In the rural population there is evidence for clustering of cases belonging to older and broader age groups, a phenomenon compatible with a delay in the development of herd immunity against putative infectious aetiological agents. The findings of the present study provide support for the hypothesis that a substantial proportion of cases of childhood leukaemia may arise as a rare sequel to exposure to an agent or agents, most probably viral in nature.

Are operative delivery procedures in Greece socially conditioned?

Caesarean section rates have increased in Greece by almost 50% during the last 13 years. We conducted a study in Athens, Greece, to assess the importance of a series of medical and socioeconomic factors in the use of Caesarean section or operative vaginal procedures, rather than a non-operative process, for the delivery of singleton, liveborn babies of primiparous mothers. We used a case control approach to compare 444 babies delivered through a Caesarean section and 130 delivered through operative vaginal delivery with 1235 normally delivered babies in a public and a private hospital. Data were analysed through multiple logistic regression. Caesarean section was more commonly performed in older, shorter or overweight mothers and for high and low birth-weight babies, as well as in response to several obstetric complications and following in-vitro fertilization. A similar pattern was noted with respect to operative vaginal delivery, except that this procedure was not unusually frequent among overweight women and was not encountered in this study among children born after in-vitro fertilization. Caesarean section was performed twice as often in the public teaching hospital as in a private maternity hospital, and operative vaginal delivery was several times more common in the former than in the latter, after controlling for biomedical risk factors. The unequal distribution of operative delivery procedures between the public and the private hospital raises questions about the justification of their performance in a substantial fraction of deliveries, and indicates that social factors condition their use.

Modulation of birthweight through gestational age and fetal growth.

Several factors are known to affect birthweight and their effects are variously mediated through gestational duration or through fetal growth conditional on this gestation. In order to quantify independent associations of birthweight conditional and unconditional on gestational age, all 2538 mothers of singleton babies delivered during 1993 in two Maternity Hospitals in Athens were interviewed and their obstetric records abstracted. Birthweight was modelled as outcome variable through multiple regression including 32 potentially predictive factors. The regression model was fitted with and without gestational age as an additional independent variable in order to apportion birthweight associations into those independent of, or mediated through, gestational length. The factors studied were found to be classifiable into the following categories: factors associated with birthweight mostly through increases in gestational duration, either positively (age at menarche, long menstrual cycles, parity 4 or higher), or negatively (single motherhood, maternal age, tobacco smoking); those associated with birthweight mostly through increase of birthweight conditional on gestational duration, either positively (male gender, short menstrual cycles, maternal pre-pregnancy weight, anaemia, oedema) or inversely (employment during pregnancy, stillbirth, primiparity, pregnancy induced hypertension, coffee drinking); and those associated with birthweight through apparently dual effects, either positively (maternal education) or inversely (perceived stress, bleeding during pregnancy). The other studied factors were not demonstrably related to birthweight in this data set. Identification and quantification of these relations is useful for understanding underlying physiological and pathophysiological processes and for increasing specificity in exploring the association of birthweight with adult onset diseases, like coronary heart disease or cancer.

Determinants of stillbirth mortality in Greece.

A population-based case-control study of the determinants of stillbirths was conducted in Greece from 1989 to 1991. All reported stillbirths after 28 weeks of pregnancy (N = 2,006) during the three year study period comprised the case group. The control group derived from random sampling of 10% of all livebirths in Greece, during the same period (N = 30,705). The data were analysed by modelling through multiple logistic regression. The adjusted relative risk of stillbirth was significantly higher for males compared to females. A statistically significant monotonic increase in relative risk was observed with shorter gestational age, low maternal education, and older maternal age. Birthweight and parity showed a statistically significant U-shaped association with stillbirth risk, with a higher risk being observed among both low and high birthweight deliveries, as well as among primiparous or multiparous (4+) mothers. Positive associations of stillbirth with multiple births, out-of-wedlock marriage and non-Greek-orthodox maternal religion were noted in crude analyses, but these associations almost disappeared in logistic regression model. Maternal urban or rural residence showed no relation to risk. Overall, the prospective risk of stillbirth after the 24th week of gestation in Greece has been estimated to be higher than that in Japan (a more developed country) with more than 40% of stillbirths occurring after the 36th week of pregnancy.

Biosocial variables and auditory acuity as risk factors for non-fatal childhood injuries in Greece.

OBJECTIVES: To examine whether biosocial variables and auditory acuity are risk factors for injuries among children. SETTING: Children with injuries who presented at the emergency clinics of one of the two university hospitals for children in Athens, Greece between December 1993 and April 1994. METHODS: 144 children aged 5-14 years, residents of Athens, were brought to the emergency clinics for a moderate to severe injury. For each of these children one hospital control, matched for age and sex, and one classmate control similarly matched were identified. A standard interview form was completed for all 432 children and acouometric and tympanometric examinations were performed in each of them. Analysis was done through conditional logistic regression. RESULTS: The likelihood of an accident was higher in children of younger fathers (odds ratio (OR) = 0.7, p = 0.04), children of mothers with non-professional jobs (OR = 1.9, p = 0.03) as well as in children of higher birth order (OR = 1.7, p = 0.01), in those with predominantly other than parental daily supervision (OR = 2.6, p = 0.001), and those with a history of previous accident (OR = 1.3, p = 0.002). Somatometric factors, school performance, use of corrective eyeglasses and subnormal auditory acuity were not found to be risk factors, but auditory imbalance and abnormal tympanograms were positively related to the risk of childhood injury (OR = 2.6, p = 0.02; and OR = 2.3, p = 0.08 respectively). CONCLUSIONS: the findings of this study underline the importance of attentive supervision and safety training of children living in modern cities; they also suggest that children with auditory imbalance and history of an accident are at higher injury risk and they should be targeted with specific intervention programs.

Factors influencing serum immunoglobulin E levels in Greek children.

Serum levels of immunoglobulin E (IgE) were determined by enzyme immunoassay in 414 Greek infants and children of both sexes, 1 month to 14 years old. The children were admitted to the "Aghia Sophia" Teaching Hospital for Children (Athens, Greece) for surgical corrections of minor anatomic abnormalities, but they were otherwise healthy. Statistical analysis was performed through multiple regression after logarithmic transformation of the immunoglobulin values. IgE levels increased significantly by about 80% per year up to the age of 5 years, without noticeable impact of age on these levels thereafter. History of allergic disease showed a significant positive association with serum levels of IgE in both younger (less than 5 years) and older children. History of frequent infections was positively associated with IgE levels, although the relation was statistically significant only in the older age group, IgE levels in Greek children appear to be higher than the corresponding levels of children living in northern Europe, but much lower than those of children in Southeast Asia, a fact that may reflect different exposure level during childhood to infections known to influence IgE levels.

Age patterns of immunoglobulins G, A & M in healthy children and the influence of breast feeding and vaccination status.

Serum levels of immunoglobulins G, A and M were determined by nephelometry in 414 infants and children aged 1 month to 14 years. The children were admitted to "Aghia Sophia" Teaching Hospital for Children for surgical corrections of minor anatomical abnormalities, but they were otherwise healthy. Statistical analysis was performed through multiple regression after logarithmic transformation of the immunoglobulin values. Immunoglobulin G (IgG) levels increased significantly by 18% per year until the age of 5 years and by 2% per year thereafter. Among children less than 5 years old, IgG levels tended to increase significantly with the number of doses of either DTP or Sabin vaccine. Immunoglobulin A (IgA) levels increased significantly by 27% until the age of 7 years and by 4% thereafter. Among children less than 7 years old, history of breast feeding was significantly associated with higher levels of IgA. Vaccination with either DTP or Sabin was associated with elevation of IgA levels among younger and, to a lesser extent, older children, but the elevations did not reach statistical significance. Immunoglobulin M (IgM) levels increased rapidly during the first 12 months of life and very slowly thereafter and they were significantly higher among girls. Among children less than one year old, there was evidence that vaccination with either DTP or Sabin was associated with elevated IgM levels, although the differences were not statistically significant possibly because of small numbers of infants in the study sample.(ABSTRACT TRUNCATED AT 250 WORDS)

Survival from childhood leukemia depending on socioeconomic status in Athens.

One hundred and twenty children first diagnosed as having acute leukemia between 1988 and 1992 in Athens, Greece, were followed until May 15, 1993. The socioeconomic status of the children's families was assessed by means of paternal occupation, paternal schooling, maternal schooling, ownership of a car, ability to choose a private medical facility and freedom in the choice of the attending physician. The analysis was done by proportional-hazards modelling, controlling for age and gender. All six socioeconomic indicators, alternatively evaluated, showed that fatality rates were higher in the lower socioeconomic groups, although nominal statistical significance was reached for only one of them. With respect to family ownership of a private car, the fatality rate ratio between children of families who own a car and children of families who do not was 0.29 with a 95% confidence interval of 0.13-0.62 (p = 0.002). These results suggest that in Greece, socially disadvantaged children have a less favorable survival from childhood leukemia.